Electrical heating-furnace.



II. v. FINNIE."

ELECTRICAL HEATING FURNACE.

APPLICATION FILED MAY I0. Isls.

2 SHEETS-SHEETNI.

Q v BY dif/IMM. N n N lq fC). N w ATTORNEYS.

ELEcTRlcAL HEATlNG EuaNAcE.

APPLICATION FILED MAY I0. 1918.

1 279, 3 1 3 Patented Sept. 17, 1918.

.` /q 3. 2 SHEETS-.SHEET 2.

INVENTOR.

- A TTORNEYS.

L flame is not uniform, the outer and inner' HERMAN V. FINNIE, 0F ST. CATHERINES ONTARIO, CANADA, ASSIGNOR TO THE CANADIAN CROCKER WHEELER CO., LIMITED, OF ST. CATHERINES, ONTARIO,

CANADA, A CORPORATION OF CANADA.

ELECTRICAL HEATivG-FURNACE.

Application ined May 1o, 1

To all whom t may concern.'

Beit known that I, HERMAN V. FINNIE, a subject of the King of England, and a resident of St. Catherines, in the Province of Ontario, Canada, have invented certain new and useful Improvements in Electrical Heating-Furnaces, of which .the followingv is a specification.

My invention relates to improved method and apparatus for electrically heating tubular structures, such as pipes, shells, or the like, and is of particular utility in the manufacture of ammunition shells for heating the ends thereof preparatory to nosing or coning of the ends. v l

Steel ammunition shells are usually first drawn out to vcylindrical form whereafter the end is heated to permit nosing thereof in suitable dies. Several methods have heretofore been employed for heating the shells, one method consisting in dipping the shellto the required depth in a bath of `molten lead, and by another method heating of the shell was accomplished by a liame, usually from an oil burner, localized to the section to be heated. These methods are objectionable, the use of lead being now prohibited Ain 1 connection with the manufacture of high eX- plosive shells on account of dangerous 4conditions that are set up when lead adhering to the shell comes in contact with high eXplo-` sives. Also, both the lead process and the liame process form a scale, which is objectionable. Furthermore, heating by lead or surfaces of the shell being heated more highly than the inner portions of the mass, and the i heating also ta (es so long that the bases of the shells become so hot that the shells cannot be handled directly but special apparatus or insulating material is necessary. t

In general, the object ofmy invention is to electrically treat shells or other tubularv Structurae in such manner that they Will be rapidly and uniformly heated, and the'heat confined to the desired zone so-as to leave the outer end ofthe shell cool enough to be readily handled by workmen with their bare hands after the heating operation. More in detail, the main feature of the invention is the cooperation of a shell or other tubular structure with the core and primary winding of an electrical transformerl in such man- Sixeciication of Letters Patent.

Patented Sept. 17,1918. 91s. serial No. 233,621.

ner'that the shell or tube when'inserte'd will constitute a secondary short-circuited winding so that the heavy current flow therethrough will rapidly anduniformly heat ,it` 'locally to the desired temperature. Another feature of the invention is such coperation of the shell or tube that when applied to the transformer it will form part of, or complete, the magnetic circuit of the core structure, the magnetic energy being then utilized to accurately position the shell or tube so that y Figure 1 is a front elevational view of the'- shell heating transformer support therefor, y

Fig.,.2 is a sectionalaview on plane 2 2,

structure and thc Fig. 3 is a sectional View on plane 3 3, Fig. 1, and.

Fig. tis a sectional view on plane 444, Fig. 2.

Describingfirstthe transformer structure, a rectangular core 5 built up of lamlnat'ions. in 'the usual manner, has the opening G through one of its lo'ng sides and thev open- A 7 in the opposite long side and concentric with the opening 6; A core section or tongue 8, also laminated, is inserted through the opening 6 to project through t'lie opening '7, the opening 7 being of larger diameterV than the core section 8 to leave-the annular space or gap 9. f

, P represents the primary or exciting wind.- ing having the leads 10 andrll whereby it may be connected to receive alternating or pulsating current therethrough. Preferably the winding is built up of a number of circu- 'lar units or coils 12 separate/d by -spacing and Ventilating strips. 13, the built-up winding being inserted in the rectangular transformer core frame to -be concentric with the core section 8. A bushing 14 of heat insu lating material is preferably inserted in the Winding and is of sufficient inner diameter to leave the annular space 15 around the core section 8. If, now, while an exciting current is flowing Kthrough the primary winding, a tubular structure t, such as a shell, is inserted through the gap 9 into the space 15 surrounded by the primary winding, this shell section within this space will constitute a closed shortcircuited secondary winding or turn and the consequent heavy current iiow through this shell zone will quickly heat it to a high temperature. The diameters of the core section 8 and that of the opening 7 are such relative to the inner and outer diameters of the shell that the shell cannot short circuit the laminations. V'Vhen the shell is inserted through the opening 7 it will form part of the magnetic circuit and practically close the annular gap 9 and the magnetic How will be as indicated by the arrows, the magnetic lines of force passing lengthwise through the shell zone within the space 15, the heavy current flow being thus induced in this Zone to heat it. The bushing 14protects the primary windig P from the intense heat generated in the s ell.

Describing now the mechanical apparatus for supporting the transformer structure, front and rear clamping frames 16 and 17 are provided, these frames being of rectangular boX shape and having lugs 18 and 19 respectively at their ends for receiving bolts 20 for drawing the frames together. The frame 16 has the opening 21 in line with the opening 7 of the core frame, while the clampingl frame 17 has the opening 22 in registrationwith the opening 6 for the corel section 8. Ridges 23 and 24 are formed on the inner sides of the clamping frames for engaging with the edges of the core frame when the clamping frames are 'drawn together, the core fra-me laminations being preferably split, that is, right and left halves, in order to overlap. The core frame is first assembled and then the primary winding coils and spacing'strips inserted within the core frame and the clamping frames are then applied and the bolts 20 tightened so that the transformer frame and the coils and spacing strips are securely clamped together. Threading through the top and bottom walls of the clamping frames are screws 25 which engage against the core frame at various points to clamp the laminations rigidly together. As the core section 8 i's subjected to the heat of the tube or shell it is preferably removable so that it can -be turned around or a new core section applied. This core section is inserted through the opening 6 of the transformer frame and is then held in place by upper and lower clamping screws 26 and 27 threading through the upper and lower walls of the clamping frame 17 and clamping the laminat-ions of the core frame against the core sections, as clearly shown in Fig. 2. When the parts are thus securely clamped together the primary winding is concentric with the core section 8 and the opening 2l is in line with the core opening 7 for the insertion of the shell to be heated.

The transformer structure is preferably mounted to be readily accessible and a number of such structures may be mounted in a row. As shown, supporting pipes 28 extend upwardly from a base 29 for receiving U- bolts 30 which extend through the upper and lower brackets 31 and 32 on the front clamping frame 1G to b`e engaged by nuts 33. The transformer structure can thus be secured at an height on the pipes 28.

gupporting means are also provided for guiding a. shell into the transformer structure and for holding it in proper position with reference to the various openings, and away from the core structure laminations. A bracket 34 is secured against the front wall of the clamping frame 16 byV screws 35 and forms the V-shaped trough 36 for supporting the Shells and guiding them centrally through the core opening 7 and into the space 15. The transformer arrangement is such that when a shell or tube of steel is inserted the polarity conditions will be such as will tend to shift the shell or tube outwardly after it has been fully inserted. This is taken advantage of to automatically obtain the proper locating of the shell or tube within the transformer so that only the desired zone will be heated. A U-shaped latch frame 37 is pivoted on lugs 38 and 39 extending laterally from the trough 36, and threading through the yoke of this latch is a set screw 40 against which abuts the outer end of the shell or tube to be heated. The shell or tube is first pushed way 'into the ytransformer and the latch raised. Upon release of the shell the magnetic forces will shift it outwardly against the abutment screw 40 which has been set so that after engagement thereof by the shell the inner end of the shell will be heated the desired distance. A spring 41 anchored to the bracket 34 and connecting with the inner end of the latch frame tends to hold the latch frame in horizontal position with its inner ends against the abutments 42 and with the set screw 40 in position to receive the shell. To enable the latch frame to be readily swung away when a shell or tube is to be inserted it iS connected by a rod 43 with a foot lever 44 secured at 45 to the base 29. The foot lever is shown of spring material to be normally held up. When a shell `is to be inserted the foot is applied to the foot lever and the latch frame is swung down away from the trough 36, and after a shell has been inserted the foot lever is released whereupon the spring action of the foot lever together with the force of spring 41 will restore the latch frame to its locking position. With the arrangement described a row of transformer structures can be quickly and accurately fed with shells or through which air can circulate to keep the primary winding'cool. To increase the flow of air through thepassageways and around the coils upper and lower housing shells 46 and 47' are secured to the clamping frames',

. the upper shell having the air inlet-48 and the lower shell the outlets 49. Air can be thus forced through the inclosure around the windings and over-heating prevented.

My invention is of general utility. for heating tubular structures or sections of other structures which are closed so that they can form a 'closed' secondary circuit whenapplied to the transformer, and heating can be for the purpose of tempering, expanding, forming or even welding, the uniformity, rapidity, localization and cleanliness of the heating being particularly useful and desirable. This 1s particularly true in the manufacture of shells where accuracy and speed are so essential.

Without limiting myself to the exact construction, operation and procedure shownandl described, changes and modifications still within the scope of the invention being possible, I claim as follows: A

1. In a heating furnace, `the combination with a transformer core having a primary energizing winding thereon and having a gap, said core having a space for receiving a'tubular structure, said gap and space being so positioned that when the tubular structure. is applied to said space it will form a closed secondary circuit and will close said gap. 2. In an electrical heating'I furnace, the

combination of a transformer core, -a primary winding thereon, a section of said core being surrounded by said winding and separated therefrom to leave an annular space for the reception of tubular structures to be heated.

3. In an electrical furnace, the combination of a transformer core having an opening at one side, a core section extending from the other side in line with said opening, a primary winding on said transformer core, said opening permitting the application to said core section of a tubular struc- `ture to [be heated by forming a closed sec-y winding surrounding said core section and spaced away therefrom to leave an annular space in line with said gap for receiving a tubular structure to be heated, the tubular structure when inserted through said annu- 7o lar gap and into said annular space acting as a closed primary windingtto be thereby subjected to heavy hea-ting current flow. 5. Injan electrical furnace, the combination of a rectangular transformer core having an opening at one side, a core section extending frorn the other side through said opening to leave an annular gap, a primary winding surrounding said core section and spaced away therefrom to leave an annular Space in line with said gap for receiving a tubular structure to be heated, the tubular structure when inserted through said annular gap and into'said annular space closing said magnetic gap and its section within 85 said annular space forming a closed secondary circuit for carrying heavy induced current iow when saidprimar'y winding is connected to a suitable source of electrical energy.

6. In an electrical furnace, the combination of a transformer frame having an opening at one side, a core section extending from the other side of said frame in line with said opening, and a primary winding surrounding said core section and spaced away therefrom to leave an annular space in line with-,said openin into which space a. tubular ,structure may ie inserted by Way' of said opening ito form a closed secondary turn for receiving heating current flow.

7. In a shellheating furnace, the combination of a core, a primary winding surrounding-:said core and separated therefrom by an annular space, and magnetic return branches extending` from one end of said core to with- -in a short distance of the other end thereof Y to leave a gap in line with said annularA space, said gap and space serving to receive a shell for completing the magnetic return 11 circuit and for forming a closed secondary turn to be thereby subjected to heavy induced current How.

8. The combination with a 'transformer frame having a primary energizing winding thereon and having a gap, of a tube inserted in said gap to complete the magnetic circuit and associated with a section of said core to be linked by 'the magnetic lines of force to thereby constitute a closed secondary turn. 12

9. In an electrical furnace, the combination of a rectangular transformer core having an opening through one side and a tongue extending from the opposite side into said opening to leave an annular gap, and a primary winding on saidl core concentric with said tongue and spaced away from said tongue to leave an annular chamber in line with said annular gap, said gap and chamber serving to receive a shell whose end will constitute a closed secondary turn to be linked by the lines of force to be thereby heated by the inducer current flow therethrough.

10. In an electrical furnace, the combination et a transformer core having an opening through one side and a tongue extending from the other side into said opening to leave an annular gap, a primary Winding on said core surrounding said tongue and spaced from said tongue to leave an annular space in line with said annular gap, a support in front of said gap for supporting shells concentrically in said gap and said space, the inner end of an inserted shell acting as a closed secondary turn to be heated by the induced current flow therethrough.

l1. In an electrical furnace, the combination of a transformer core having an opening through one side and a tongue extending from the other side into said opening to leave an annular gap, a primary winding o-n said core surrounding said tongue and spaced from said tongue to leave an annular space in line with said annular gap, a support in front of said annular gap for shells to be heated, an adjustable stop on said support for holding a shell thereon. with its inner end extending the desired distance into said annular space, such inner end constituting a closed secondary turn around said tongue to be linked by the lines of force through said core and to be highly heated by the nduced current flow therethrough.

12. In an electrical furnace, the combination of a transformer core having an opening through one side and a tongue extending from the other side into said opening to leave an annular gap, a primary winding on said coresurrounding said tongue and spaced from said tongue to leave an annular space in line with said annular gap, a support along which a shell can be inserted through said annular gap and into said annular space to be concentrictherewith, the shell when inserted setting up polarity conditions which tend to force the shell outwardly after insertion thereof, and an adjustable stop on said support for receiving the shell and for holding it in position with its inner end eX- tending the desired distance into the annular space, said inner end forming a closed secondary turn which is linked by the magnetic lines of force and heated by the induced current How therein.

13. In an electrical furnace, the combination of a transformer core having an opening through one side and a tongue extending from the other side into said opening to leave an annular gap, a primary winding on said core surrounding said tongue and spaced from said tongue to leave an annular space in line With said annular gap, a clamping frame surrounding and clamping together said transformer, core and primary winding, said frame having a passageway in line with said annular gap and annular space, a supporting and guiding Ibracket for shells to be heated secured to said frame, a shell when inserted through said annular gap and space being held concentric therewith by said bracket, the inserted shell completing the magnetic circuit and the resulting polarity conditions tending to shift said shell outwardly after insertion thereof, and an ad? justable abutment on said bracket for receiving the outer end of said shell to hold its inner end the required distance in said annular space, such inner end forming a closed secondary turn linked by the magnetic lines of force and heated by the induced lines of current iiow throughout,

In witness whereof, I hereunto subscribe myv name this lst day of May, A. D., 1918. HERMAN V. FINN IE. 

